Extremely tentative, partial, and probably wrong answer
Some of the clues suggest that you might be
I represent both joy and fear
To quote Wikipedia:
"In Europe and America orange and yellow are the colours most associated with amusement, frivolity and entertainment. In this regard, orange is the exact opposite of its complementary colour, blue, the colour of calm and reflection. Mythological paintings traditionally showed Bacchus (known in Greek mythology as Dionysus), the god of wine, ritual madness and ecstasy, dressed in orange."
and, on the other hand,
"Orange is the colour most easily seen in dim light or against the water, making it, particularly the shade known as safety orange, the colour of choice for life rafts, life jackets or buoys. Highway temporary signs about construction or detours in the United States are orange, because of its visibility and its association with danger."
Note that this all fits reasonably well with HINT #1.
I eat children by the piece, and they eat me too
I don't understand the first part if this is right -- but children certainly eat oranges.
I am now retired, but I like to explore my land
I don't understand the first part if this is right, but there are plenty of places called Orange.
If you've seen it you know I'm never settled
... Most of them have plenty of inhabitants, though, and my guess is that "never settled" means "never inhabited by people". There doesn't appear to be any Arctic or Antarctic region called Orange.
They used to see me around not so long ago
Don't understand this either.
Hint #1 I mentioned above. #2 is obvious. #3 might refer to
the Hare Krishnas (more formally the International Society for Krishna Consciousness) who exist in the USA as well as many other places, and wear orange robes. Or it might (I hope not) be some sort of allusion to the current President of the USA...
Hint #4 I don't understand if this answer is right; again
I hope it isn't a reference to the current POTUS.